ISSN print edition: 0366-6352 ISSN electronic edition: 1336-9075 Registr. No.: MK SR 9/7 Published monthly

Temperature-dependent volumetric and viscometric properties of amino acids in aqueous solutions of an antibiotic drug

Suvarcha Chauhan, Poonam Chaudhary, Kundan Sharma, Kuldeep Kumar, and Kiran

Department of Chemistry, Himachal Pradesh University, Summerhill, Shimla, 171005, India

E-mail: chauhansuvarcha@rediffmail.com

Abstract: Volumetric and viscometric properties of glycine and methionine (amino acids) in a 0.2 vol. % amikacin sulphate (antibiotic drug) aqueous solution with the molality range of 0.025 mol kg⁻¹–0.25 mol kg⁻¹ were measured over the temperature range of 20°C–40°C at the interval of 5°C. Different parameters like apparent molar volume (ϕ_V), apparent molar adiabatic compression (ϕ_κ), isentropic compression (κ_S) along with other acoustical parameters were calculated. Parameters like viscous relaxation time (τ), free volume (V_F), internal pressure (Π_I), and molar cohesive energy (MCE) were calculated from dynamic viscosity measurements. The ϕ_V values are positive in both cases, but with higher magnitude observed in methionine. These positive values of ϕ_V are indicative of strong solute-solvent interactions at all temperatures. In case of methionine there is a sharp initial increase in the ϕ_V values which become almost constant with further additions of the amino acid. Structural differences in the two amino acids studied are clearly reflected in the different nature of the plots of different parameters. In case of an amino acid-drug system, dynamic viscosity increase has been attributed to the increase in the hydrophilic-ionic and hydrophilic-hydrophilic interactions with the increase in the amino acid concentration which in turn may cause more frictional resistance to the flow of the solution. All other parameters are discussed in terms of solute-solvent and solvent-solvent interactions.

Keywords: amikacin sulphate – apparent molar adiabatic compression – apparent molar volume – glycine – leucine

Full paper is available at www.springerlink.com.

DOI: 10.2478/s11696-013-0404-y

Chemical Papers 67 (11) 1442–1452 (2013)